Cytotoxicity versus transforming activity in chemically exposed Syrian hamster embryo cells

A series of experiments was conducted to determine the dose response relationship with respect to both cytotoxicity and morphological transformation in Syrian hamster embryo cells exposed to different chemicals. The effects of the following model chemical carcinogen/mutagens were investigated: 3-methyl cholanthrene (3-MC), benzo(a)pyrene (B(a)P), N-methyl-N-nitro-N-nitroso-guanidine (MNNG), N-methyl-N-nitrosourea (MNU), the noncarcinogenic weak mutagen methyl methanesulfonate (MMS) and nonmutagenic pesticides Supercypermethrin EC, VUCHT 524, and Dual. The results showed that all carcinogen/mutagens, i.e. 3-MC, B(a)P, MNNG, and MNU increased the number of morphological transformations on the maximum level at concentrations < TD50-TD70 (TD = toxic dose) and remained more or less on the same level at higher concentrations. Similar effect was observed in embryo cells treated with nonmutagenic Supercypermethrin EC. Very low concentrations of nonmutagenic pesticide VUCHT 524 stimulated proliferation of cells and at the same time induced the maximum level of morphological transformations. MMS and Dual did not induce morphological transformation of embryo cells at all. Induction of morphological transformation in embryo cells is evidently independent of the activity of a chemical to induce gene mutations and seems to be a valuable assay for studying the carcinogenic effects of lower doses of suspicious chemicals.